Word of advice for any good or exiled players needing to go to neriak. The epics and mobs in general have a very very short leash range. You can walk about 10 feet and they break.
Also I too am bugged at the same step on Naggy and would much appreciate any help from anyone I can get.
Yeah I got my epic like three days ago? No idea why he isn't spawning for you. However evacing did bug him out so he didn't spawn his adds, on a near whipe while I was trying to underman it.
The update today did not fix the bug. You have to wait for a server reset and he will spawn, IF your the first to hit him. Sometimes deleting the dagger will get him to spawn but not sure.